Commonwealth countries must act now to end modern slavery, according to a petition signed by more than 64,000 people.
The statement, which calls on the heads of Commonwealth countries to commit to ending the scourge, was given to Nabeel Goheer, assistant secretary-general of the Commonwealth.
The petition, drawn up by anti-slavery campaign group Freedom United, came ahead of the Commonwealth Summit to take place at Buckingham Palace and Windsor Castle this week.
Urmila Bhoola, UN special rapporteur for modern slavery, said the petition shows there is "considerable public support" for the Commonwealth formally vow to eradicate human trafficking, forced labour and other forms of slavery.
She said: "We should be shocked that slavery exists on the scale it does today. Whilst the Commonwealth and slavery have a shocking history, this is an important opportunity for the Commonwealth to make history as a leading body in the anti-slavery movement."
After this week's conference, leaders from Commonwealth countries will lay down an agreement that activists hope will include a pledge to fight slavery that would bring them in line with UN Sustainable Development Goals set in 2015 to tackle the crime.
Commonwealth countries are currently home to a disproportionately high number of horrific human trafficking and forced labour cases.
Figures from the Global Slavery Index show that 55 per cent of today's modern slaves are living in Commonwealth countries - even though only a third of the world's people live in the Commonwealth.
Evening Standard comment: Modern slavery is a scourge we can tackle
The petition came as the Commonwealth Human Rights Initiative (CHRI) also launched a pioneering report detailing slavery in every country in the Commonwealth in a series of previously unpublished profiles.
The report makes recommendations for the Commonwealth to get on track, including the ratification of existing international laws against slavery.
The Evening Standard's three-month investigation last year exposed the scale of modern slavery in London, from sex trafficking to those forced to work in car washes and on building sites.
The campaign included launching a digital platform to take actions against slavery, such as taking part in a demonstration through central London, in partnership with Freedom United.
The Independent Anti-Slavery Commissioner estimates there are at least 13,000 modern slaves in the UK alone.
The Commonwealth Heads of Government meeting this week is seen as a highly significant moment in the history of the organisation, as it is likely to be the last personally hosted by the 92-year-old Queen as she scales down her public duties.